Method for transmitting information on position on digital map and device used for the same

ABSTRACT

A method of transmitting position information of a digital map capable of transmitting a position on a digital map efficiently and accurately in which a transmitting side transmits position information including coordinate series information for specifying a vector shape on a digital map and a receiving side execute map matching by the coordinate series information to thereby identify the vector shape on the digital map, the coordinate series information is transmitted by adding azimuth information of a coordinate point included in the coordinate series information thereto. By transmitting shape data by adding the azimuth information thereto, accuracy of matching can be promoted and necessary time for matching can be shortened.

TECHNICAL FIELD

The present invention relates to a method of transmitting positioninformation of a digital map and an apparatus utilized for the method,particularly, enabling to transmit a position on a digital mapefficiently and precisely.

BACKGROUND ART

In recent years, vehicles mounted with navigation vehicle-mountedapparatus have rapidly been increased. The navigation vehicle-mountedapparatus holds a data base of a digital map and displays traffic jam orposition of traffic accident on a map based on traffic jam informationor traffic accident information provided from a traffic informationcenter or the like, further, executes search for route by adding theseinformation to conditions therefor.

Although the database of the digital map is formed by several companiesin Japan, due to a difference in basic drawings and digitizingtechnology, the map data includes error and the error differs by thedigital maps of the respective companies.

In the case of transmitting, for example, a position of traffic accidentby traffic information or the like, when longitude and latitude data ofthe position is provided by itself, according to the vehicle-mountedapparatus, there is a concern that a position on a different road isidentified as the position of the traffic accident depending on kinds ofthe data base of the digital map held.

In order to improve such inaccuracy of information transmission,conventionally, a node number is defined at a node such as a crossroadspresent in a road network, further, a link number is defined for a linkrepresenting a road between nodes, according to the digital map database of the respective companies, respective crossroads and roads arestored in correspondence with node numbers and link numbers, further, intraffic information, a road is specified by a link number and a spot onthe road is displayed by an expression method stating some meters from ahead thereof.

However, a node number or a link number defined in a road network, needsto switch to a new number in accordance with newly laying or changingroads, further, when a node number or a link number is changed, thedigital map data of the respective companies must be updated. Therefore,according to a system of transmitting position information of a digitalmap by using a node number or a link number, enormous social cost isrequired for maintenance thereof.

In order to improve such a point, the inventors of the invention haveproposed, in Japanese Patent Application No. 214068/1999, a system inwhich in order to transmit a road position, an information providingside transmits “road shape data” comprising coordinate series indicatinga road shape of a road section having a predetermined length includingthe road position and “relative position data” indicating the roadposition in the road section represented by the road shape data and aside of receiving the information specifies the road section on adigital map by executing map matching by using the road shape data andspecifies the road position in the road section by using the relativeposition data, further, the inventors have proposed, in Japanese PatentApplication No. 242166/1999, a system of also transmitting “additionalinformation” such as kind of road, road number, a number of crossinglinks of nodes, angles of crossing links, name of crossroads and so onin a road section such that map matching on the receiving side canaccurately be executed even when a transmission data amount of the “roadshape data” is reduced, further, proposed a system of thinning thetransmission data amount of the “road shape data” within a range bywhich erroneous matching on the receiving side is not brought about.

In this case, the map matching on the receiving side is carried out, forexample, as follows.

As shown by FIG. 45, when as “road shape data” representing a road shapeof a road bringing about traffic jam in section A through B, longitudeand latitude data of spots P₀ (x₀, y₀), P₁ (x₁, y₁), . . . , P_(k)(x_(k), y_(k)) are transmitted as follows,

-   -   (x₀, y₀) (x₁, y₁) . . . (x_(k), y_(k)),        as shown by FIG. 44, the receiving side selects roads included        in a range of error centering on spot P₀ (x₀, y₀) by using map        data read from a digital map data base of its own as candidates        and narrows down candidates therefrom by using transmitted        “additional information”. When a single candidate is narrowed        down, positions most proximate to (x₀, y₀) and (x_(k), y_(k)) of        the road are calculated and the section is defined as a road        section represented by “road shape data”.

When the single candidate is not narrowed down and roads Q and R remainas candidates, positions Q₀ and R₀ on the respective candidate roadsmost proximate to P₀ (x₀, y₀) are calculated and distances between P₀through Q₀ and P₀ through R₀ are calculated. The operation is executedfor respective points P₁ (x₁, y₁) . . . , P_(k) (x_(k), y_(k)) A roadsection minimizing a value produced by adding square means of thedistances from respective points P₀, P₁, . . . , P_(k) is calculated andthe road section is specified by a method of determining the roadsection as a road section represented by the “road shape data”.

The traffic jam section of A through B is specified based on thetransmitted “relative position data” with a position of starting theroad section calculated from the “road shape data” as onset.

When position information on a digital map is transmitted by trafficinformation or the like, it is necessary to transmit data such that acorrect position can be recognized by a counterpart in a short period oftime.

Further, as a case of transmitting position information on a digitalmap, there is assumed a case of transmitting information of a disastersite in mountains or accident at rivers and therefore, it is alsonecessary to transmit a map shape of other than roads or positioninformation of a spot other than roads.

The invention responds to such problems and it is an object thereof toprovide a method of transmitting position information of a digital mapfor further improving a method of transmitting position information of adigital map by using “shape data” specifying a map shape on the digitalmap and “relative position data” specifying a relative position in themap shape specified by the “shape data”, capable of transmitting aposition on the digital map efficiently and accurately, further, capableof transmitting also position information other than a road shape of aspot on a road, further, provide an apparatus used therefor.

DISCLOSURE OF INVENTION

Hence, according to the invention, there is provided a method oftransmitting position information in which transmitting side transmitsposition information including coordinate series information forspecifying a vector shape on a digital map and a receiving side executesmap matching by the coordinate series information to thereby identifythe vector shape on the digital map wherein the coordinate seriesinformation is transmitted by adding intercept azimuth information of acoordinate point included in the coordinate series information thereto.

Further, the coordinate series information is transmitted by addinginformation of a height of a coordinate point included in the coordinateseries information thereto.

Further, the coordinate series information includes position informationof a coordinate point and information of a function approximating thevector information passing through the coordinate point.

Further, the coordinate series information is constituted by informationdesignating coordinate series information of a reference and informationprescribing a distance and a direction of offset with regard to thecoordinate series information of the reference.

Further, a coordinate value of a digital map representing the vectorshape is included in the coordinate series information by making thecoordinate value transit in a range by which erroneous matching is notproduced.

Further, relative distance information from a reference point set at amiddle of the vector shape is included in the position information.

Further, event information made to directly correspond to a coordinatepoint of the coordinate series information is included in the positioninformation.

Further, a direction identifying flag is included in the positioninformation and a vehicle advancing direction influenced by an eventproduced at a road is clearly indicated by the direction identifyingflag.

Further, a direction identifying flag is included in the coordinateseries information and a situation of one way traffic regulation of aroad specified by the coordinate series information is clearly indicatedby the direction identifying flag.

Further, a plurality of reference points are set in the road shape andinformation of travel time between the reference points is included inthe position information.

Further, a vector shape of other than a road is specified by thecoordinate series information.

Further, the transmitting side transmits the position information byincluding coordinate series information and reference point relativeposition information for specifying one or more of reference points andrelative position information of a target position with respect to thereference points thereto and the receiving side identifies the vectorshape on the digital map by executing the match mapping by thecoordinate series information, specifies positions of the referencepoints in the vector shape by using the reference point relativeposition information and specifies the target position by using therelative position information of the target position with respect to thereference points.

Further, the receiving side restores coordinate series information ofcoordinate points at equal intervals from the coordinate seriesinformation and executes map matching by using the restored coordinateseries information.

Further, there is constituted an apparatus of restoring a coordinateseries for restoring coordinate series information of coordinate pointsat equal intervals from coordinate series information subjected to datacompression for specifying a vector shape on a digital map.

According to the method of transmitting position information of adigital map of the invention, the position on the digital map canefficiently and accurately be transmitted.

By transmitting the coordinate series information by adding interceptazimuth information, height information, one way traffic information bya direction identifying flag or the like, accuracy of matching can bepromoted and necessary time for matching can be shortened.

By approximating the vector shape by a function or displaying shape dataof an up and down way separating road by an offset distance, a dataamount can be reduced and a data transmission efficiency can bepromoted.

By setting a reference point at a crossroads or the like in a roadsection and displaying a relative distance to an event position ordescribing the event position by a node number, accuracy of specifyingthe event position on the receiving side can be promoted.

Further, by using the direction identifying flag, a vehicle advancingdirection influenced by an event can be specified.

Further, data can be transmitted by modifying the data in the form oftransmitting travel time.

Further, the invention is applicable also to transmission of vector dataof other than a road, further, a position outside of a road on thedigital map can also be transmitted.

Further, the method and the apparatus for restoring data at equalintervals from a compressed shape data series, can promote a matchingefficiency on the receiving side.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view for explaining shape data of First Embodiment,

FIG. 2 is a flowchart showing a procedure of forming shape data on atransmitting side according to First Embodiment,

FIG. 3 is a diagram showing node series information according to FirstEmbodiment,

FIG. 4 is a view for explaining map matching on a receiving sideaccording to First Embodiment,

FIG. 5 is a flowchart showing a map matching procedure on the receivingside according to First Embodiment,

FIG. 6 is a view for explaining shape data of Second Embodiment,

FIG. 7 is a diagram showing node series information according to SecondEmbodiment,

FIG. 8 is a diagram showing node series information adopting otherexpressing method according to Second Embodiment,

FIGS. 9(a), 9(b), and 9(c) illustrate views indicating a reduction indata according to Third Embodiment,

FIG. 10 is a diagram showing node series information according to ThirdEmbodiment,

FIG. 11 is an explanatory view of a double-streaked line,

FIG. 12 is a view for explaining shape data according to FourthEmbodiment,

FIG. 13 is a view explaining a direction of offset according to FourthEmbodiment,

FIG. 14 is a diagram showing node series information on a master sideaccording to Fourth Embodiment,

FIG. 15 is a diagram showing node series information on a side ofreferring to the master according to Fourth Embodiment,

FIG. 16 is a view for explaining shape data by other system according toFourth Embodiment,

FIG. 17 is a view for explaining shape data according to FifthEmbodiment,

FIG. 18 is a flowchart showing a procedure of forming shape dataaccording to Fifth Embodiment,

FIG. 19 is a flowchart showing a procedure of determining a transitionvalue according to Fifth Embodiment,

FIG. 20 is a view for explaining a reference point according to SixthEmbodiment,

FIGS. 21(a), 21(b), and 21(b) are diagrams showing node seriesinformation, road additional information, and event informationaccording to Sixth Embodiment,

FIGS. 22(a) and 22(b) are diagrams showing node series information andevent details information according to Seventh Embodiment,

FIGS. 23(a) and 23(b) are diagrams showing node series information andevent information according to Seventh Embodiment,

FIG. 24 is a view for explaining an event occurring situation accordingto Eighth Embodiment,

FIG. 25(a), 25(b), and 25(c) are diagrams showing node seriesinformation, road additional information and event information accordingto Eighth Embodiment,

FIG. 26 is a view for explaining a one way traffic situation accordingto Eighth Embodiment,

FIG. 27 is a diagram showing node series information representing oneway traffic according to Eighth Embodiment,

FIG. 28 is a flowchart showing a map matching procedure according toEighth Embodiment,

FIG. 29 is a diagram showing event information representing an event ofa double-streaked line according to Eighth Embodiment,

FIG. 30 is a view for explaining travel time according to an eightembodiment,

FIG. 31(a), 31(b), and 31(c) are diagrams showing node seriesinformation, road additional information, and necessary time informationaccording to Eighth Embodiment,

FIG. 32 is a block diagram showing a constitution of a positioninformation transmitting/receiving apparatus according to TenthEmbodiment,

FIGS. 33(a), 33(b), and 33(c) illustrate views for explainingcompression and decoding of shape data according to Tenth Embodiment,

FIG. 34 is a view showing facility shape vectors in a digital map,

FIG. 35 is a diagram showing vectors representing a prefectural boundaryshape, contour lines, and a lake or marsh shape in a digital map,

FIG. 36 is a diagram showing node series information of a house shapeaccording to Eleventh Embodiment,

FIG. 37 is a diagram showing node series information of a water areashape according to Eleventh Embodiment,

FIG. 38 is a diagram showing node series information of anadministrative boundary shape according to Eleventh Embodiment,

FIG. 39 is a diagram showing node series information of a contour lineshape according to Eleventh Embodiment,

FIG. 40 is a view for explaining a method of expressing a positionoutside of a road according to Twelfth Embodiment,

FIG. 41 is a flowchart showing a procedure of reproducing a positionaccording to Twelfth Embodiment,

FIG. 42 is a view for explaining other method for expressing a positionoutside of a road according to Twelfth Embodiment,

FIG. 43 is a flowchart showing other procedure of reproducing a positionaccording to Twelfth Embodiment,

FIG. 44 is a view for explaining an example of map matching,

FIG. 45 is a view for explaining road shape data and relative positioninformation,

FIG. 46 is a view for explaining a intercept azimuth,

FIG. 47 is a view for explaining a method of restoring data in a sectionapproximated by a straight line according to Tenth Embodiment,

FIG. 48 is a view for explaining a method of restoring data at a sectionapproximated by a function according to Tenth Embodiment,

FIG. 49 is a view for explaining a method of expressing coordinates of anode by a distance and an argument between the node and a precedingnode,

FIGS. 50(a), 50(b), and 50(c) are diagrams showing node seriesinformation representing coordinates of a node by a distance and anargument between the node and a preceding node,

FIGS. 51(a) and 51(b) are views schematically showing shape datarepresenting coordinates of a node by a distance and an argument betweenthe node and a preceding node,

FIG. 52 is a view schematically showing a map matching processing whencoordinates of a node are represented by a distance and an argumentbetween the node and a preceding node, and

FIG. 53 is a view showing a way of calculating a successive candidatepoint in the map matching processing when the coordinates of the nodeare represented by the distance and the argument between the node andthe preceding node.

The numerals in the drawings are 10, 20 position informationtransmitting/receiving apparatus, 11, 22 position information receivingportion,12 node series restoring portion,

-   -   13 map matching portion, 14 digital map data base, 15 digital        map displaying portion, 16 event information inputting portion,        17 position information converting portion, and 18, 21 position        information transmitting portion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

In First Embodiment, an explanation will be given of a method oftransmitting position information for promoting accuracy of map matchingfor specifying a road section on a receiving side by transmitting shapedata by adding intercept azimuth information thereto.

An explanation will be given of an example of a case of transmittinglongitude data and latitude data of respective spots indicated by blackcircles as shape data in order to transmit a road shape from P₁ to P_(N)of a road 2 shown in FIG. 1. Here, the black circles represent nodes andinterpolation points of nodes on the roads included in a digital mapdatabase. A node is set in correspondence with a crossroads, an inlet oran outlet of a tunnel, an inlet or an outlet of a bridge, a boundary ofadministrative sections or the like and is attached with a node number.An interpolation point is a point set for reproducing a road shapebetween nodes. In this case, a node and an interpolation point areinclusively referred to as nodes so far as not particularly specifiedotherwise.

Although longitude data and latitude data of respective nodes are storedin digital map databases on a transmitting side and a receiving side, asmentioned above, data respectively include error.

The transmitting side transmits shape data indicating road shape byincluding longitude and latitude data of P₁, P₂, . . . , P_(N) , inorder to reduce a data amount, longitude and latitude data of P₁ isdisplayed by absolute coordinate values (longitude, latitude) andlongitude and latitude data of P₂, . . . , P_(N) are displayed byrelative coordinate values indicating differences from the longitude andlatitude data of P₁, or differences from longitude and latitude data ofa preceding node.

As shown by a dotted line arrow mark of FIG. 1, intercept azimuthinformation included in the shape data is information of azimuth of anintercept at a position of the respective node, that is, azimuth of atangential line in contact with a road curve at node p_(X).

As shown by FIG. 46, the intercept azimuth at the node position isdisplayed in a range of 0 degree through 360 degrees in the clockwisedirection by defining an absolute azimuth of due north as 0 degree. Theintercept azimuth of the node P_(X) can be calculated as follows when acontiguous node disposed on the upstream side of the node p_(X) isdefined as p_(X−1) and a contiguous node disposed on the downstream sideof the node p_(X) is defined as p_(X+1), by averaging an azimuth θ_(X−1)of a straight line connecting node p_(X−1) and node p_(X) and an azimuthθ_(X) of a straight line connecting node P_(X) and p_(X+1).(θ_(X−1)+θ_(X))/2

FIG. 2 shows a procedure of calculating an intercept azimuth ofrespective node on a transmitting side as follows.

Step 91: Sample respective node position from map data,

Step 92: Sample intercept azimuth of respective node position.

Intercept azimuths of respective nodes sampled in this way aresummarized as node series information representing shape data along withlongitude and latitude data of respective nodes as shown by FIG. 3. Thenode series information is aligned with kinds of vector data representedby node series (in this case, “road”), a total number of nodes (Npieces) and longitude and latitude data and intercept azimuth data withregard to respective nodes starting from node No. P₁. Although longitudeand latitude data and intercept azimuth data of node No. P₁ aredisplayed by absolute coordinates and an absolute azimuth, longitude andlatitude data and intercept azimuth data of from node No. P₂ throughnode No. P_(N), are displayed by relative coordinates and relativeazimuths in order to reduce a data amount.

The node series information is converted into a transmission formatalong with relative position data representing positions of events inthe road section represented by the node series information and istransmitted.

The receiving side receiving the node series information and relativeposition data executes map matching and specifies the road sectionrepresented by the node series information. FIG. 5 shows a procedure inmap matching.

Step 121: Sample a position on the road proximate to the longitude andlatitude data of node No. P_(X) as a matching candidate in an order ofproximity,

Step 122: Calculate a difference between a section azimuth of thecandidate position and a section azimuth of P_(X). When the differenceis smaller than a prescribed value, the matching candidate isconstituted to thereby constitute an object of map matching explained inreference to FIG. 44.

Further, when the difference is larger than the prescribed value, thecandidate is excluded from the matching candidate, the operation returnsto step 121, samples a next proximate one as a matching candidate andexecutes the procedure of step 122.

Although in FIG. 1, spot P_(X) on road 2 is liable to be erroneouslymatched to road 1 constituting the most proximate road, as shown by FIG.4, on the receiving side, in matching, by comparing intercept azimuthsof matching candidate point 1 on road 1 most proximate to spot P_(X) andspot P_(X), matching candidate point 1 can be excluded from thecandidate and matching candidate 2 on road 2 next proximate to spotP_(X) can remain as the candidate.

In this way, according to the method of transmitting positioninformation of the embodiment, by including the intercept azimuthinformation to the position information, matching accuracy on thereceiving side is promoted and the candidate can be narrowed down in ashort period of time. Therefore, on the receiving side, the transmittedposition on the digital map can accurately and swiftly be recognized.

Further, although according to the embodiment, an explanation has beengiven of the case of including coordinates data of nodes andinterpolation points of a road to shape data indicating road shape,coordinate points may be resampled at constant intervals on the roadshape and the shape data indicating the road shape may includecoordinate data of the coordinate points.

Second Embodiment

In Second Embodiment, an explanation will be given of a method oftransmitting position information for transmitting shape data by addingdata of height.

FIG. 6 schematically shows vector data series representing a road in thecase of representing digital map data in three dimensions of longitude,latitude and height.

In this case, the transmitting side transmits node series information ofshape data by including X direction coordinate (longitude), Y directioncoordinate (latitude) and Z direction coordinate (altitude) ofrespective node as shown by FIG. 7.

On the receiving side, similar to the intercept azimuth information ofFirst Embodiment, in matching, candidate points can be narrowed down byreferring to Z direction coordinate of matching candidate pointsselected based on distances on X-Y plane and transmitted positions onthe digital map can accurately and swiftly be recognized.

Further, although Z direction coordinate of respective node isrepresented by altitude, the Z direction coordinate may be displayed bya height from the surface of the ground. By including data of the heightfrom the ground surface to the shape data in this way, a high level roadcan be discriminated from a general road passing therebelow.

Further, as shown by FIG. 8, the Z direction coordinate of respectivenode may be displayed by a slope between the node and a preceding node.

Third Embodiment

According to Third Embodiment, an explanation will be given of a methodof transmitting position information for reducing a transmitted dataamount by approximating shape data by a function.

In a vector data series from P₁ to P_(n) shown in FIG. 9(a), shapes fromP₁ through P_(m1) and P_(m1) through P_(m2), are approximated by a basicfunction F (h, r₁, r₂) such as a cosine curve shown in FIG. 9(c).Notations h, r₁, and r₂ designate parameters of the function.

By executing the approximation, as shown by FIG. 9(b), P₁ through P_(m2)can be represented by coordinates data of P₁, P_(m1) and P_(m2), afunction approximating an interval of P₁ through P_(m1), indicated by F(a, b, c) and parameters thereof and a function approximating aninterval of P_(m1), through P_(m2) indicated by F (d, e, f) andparameters thereof to thereby enable to reduce the data amount.

FIG. 10 shows node series information in this case.

On the receiving side, when the shape data is received, between P₁ andP_(m2), there is calculated a shape represented by F (a, b, c) and F (d,e, f) from coordinates data of P₁, P_(m1) and P_(m2) and parametersthereof and map matching is executed by setting spots at arbitraryintervals on the shape.

In this case, the shape represented by F (a, b, c) and F (d, e, f) maynot coincide accurately with the shapes from P₁ through P_(m1) andP_(m1) through P_(m2) of FIG. 9(a) but may be approximated thereto to adegree of not causing erroneous matching on the receiving side.

According to the method of transmitting position information of theembodiment, the transmitted data amount can considerably be reduced andefficient formation of data transmission can be achieved.

Fourth Embodiment

In Fourth Embodiment, an explanation will be given of a method oftransmitting position information for transmitting road shape data ofparallel roads by a small data amount.

As shown by FIG. 11, an express way or a toll road is expressed by aroad separating up and down ways in a number of digital maps and isreferred to as double-streaked line. In the case of the double-streakedline, as shown by FIG. 12, road shape data of one road (road 2) utilizesroad shape data of other road (road 1) to thereby enable to compress adata amount.

In this case, node spots P₁′, P₂′, . . . , P_(n)′ of road 2 can beapproximated as spots produced by moving road spots P₁, P₂, . . . ,P_(n) in road 1 to a right side (or left side) of road 1 by a constantoffset distance (L). As shown by FIG. 13, a direction of offset is adirection orthogonal to a intercept direction of each of the node spotsP₁, P₂, . . . , P_(n) of road 1.

As shown by FIG. 14, in node series information, there are described ashape vector series identifying number constituting an identifyingnumber of shape data at top thereof and a reference vector series numberrepresenting shape data to be referred. In node series information ofroad 1 constituting a master, the reference vector series number becomes“none” and there are described longitude and latitude data and interceptazimuth data for respective nodes similar to the first embodiment (FIG.3).

Meanwhile, as shown by FIG. 15, node series information of road 2referring to the shape data of road 1 describes a shape vector seriesidentifying number of road 2, a reference vector series numberrepresenting the shape data of road 1 of the reference, an offsetdistance and an offset direction (right or left of node seriesconstituting master).

In this way, in the case of parallel roads, by utilizing road shape dataof one road, shape data of other thereof is expressed to thereby enableto reduce considerably a data amount to be transmitted.

Further, although according to the system, other road is mapped andreproduced by offsetting one existing road shape of a double-streakedline by a constant distance, in this case, there is a drawback thaterror is increased at an abrupt curve portion having a large radius ofcurvature. In order to reduce error of a reproduced position as small aspossible by mapping, as shown by FIG. 16, there may be constructed aconstitution in which a center line of the double-streaked line iscalculated, the nonexisting “assumed center line shape vector dataseries” is transmitted as a master, both of shape data of an up routeand down route refer to the master and are prescribed only by the offsetdistance and the offset direction.

Further, although an explanation has been given here of adouble-streaked line, the system of the embodiment is also applicable byconstituting an object by roads in a lattice shape in which the numberof roads run in parallel.

Fifth Embodiment

In Fifth Embodiment, an explanation will be given of a method oftransmitting position information for modifying and transmitting shapedata.

According to the method of transmitting position information of theembodiment, original map shape is more or less deformed to a degree ofnot causing erroneous matching on the receiving side and transmitted.

FIG. 17 schematically shows deformation of shape data in this case. Whenan original position provided to map data is defined as P_(X), theposition is modified to a position of P_(X)′. At this occasion, adistance (transition value B) from P_(X) to P_(X)′ is set based on adistance L from spot P_(X) to a contiguous road, further, an azimuth(transition azimuth θ) P_(X) to P_(X)′ is determined by a random number.

FIG. 18 shows a procedure of calculating P_(X)′.

Step 261: Sample node position P_(X) from map data,

Step 262: Calculate distance L to contiguous road,

Step 263: Determine transition value B.

In determining the transition value B, by a procedure shown in FIG. 19,

step 271: Calculate B by B=L×β₁. Here, β₁ is a value less than 1previously determined by the system (for example, β₁=0.1).

Step 272: Compare B calculated at the step 271 with β₂. β₂ is a distancepreviously determined by the system (for example, β₂=150 m). When B>β₂,

Step 273: Determine B as B=β₂.

Further, in step 272, when B□β₂, the value calculated at step 271 isdetermined as B.

When the transition value B is determined in this way,

step 264: Determine transition azimuth θ by the following equation.θ=R×360 (degree)

Here, notation R designates a random number generating function and is auniform random number of 0 through 1. Further, notation θ represents anabsolute azimuth of 0 degree through 360 degrees in the clockwisedirection by defining an absolute azimuth of due north by 0 degree.

Step 265: Calculate coordinates P_(X)′ after transition by using thedetermined transition value B and transition azimuth θ.

By such procedure, the map data can be deformed to a degree of notcausing erroneous matching on the receiving side.

Further, as a method of deforming map data, otherwise, there can also beused a method of calculating the coordinate P_(X)′ after transition byadding a random number C in the latitude direction and adding a randomnumber D in the longitude direction to the coordinate value of P_(X), ora method of determining a transition value from an original position toconstitute a normal distribution of σ=A.

Sixth Embodiment

In Sixth Embodiment, an explanation will be given of a method oftransmitting position information for specifying a relative position ina road section specified by shape data by using a reference pointpertinently defined in the road section and transmitting theinformation.

As shown by FIG. 20, when a node series from P₁ through P_(n) istransmitted by shape data and transmitting a position of trafficaccident therein, according to a method of the embodiment, a node P₄ ofa crossroads in the midst of a node series is defined as a referencepoint and the position of traffic accident is displayed by a relativedistance from P₄.

Further, traffic jam caused in the road section is displayed by arelative distance from a node P_(x) of a T-road as a reference point.

Relative position information displayed by using the reference pointdefined in the road section in this way, is transmitted to the receivingside by data shown in FIGS. 21(a), 21(b), and 21(c).

FIG. 21(a) is node series information specifying the road section. FIG.21(b) is road additional information proposed by Japanese PatentApplication No. 242166/1999 displaying a node number linked to the nodeseries information, a number of connection links of crossroads andconnection link angles of the respective connection links with respectto crossroads nodes included in the road section for respectivecrossroads nodes along with a road kind code, a road number and a tollroad code of the road constituting an object.

FIG. 21(c) shows event information for displaying a relative position inthe road section and event content of event occurring at the positionand the relative position is displayed by a relative distance from areference point indicated clearly.

By defining a node easy to identify such as a crossroads in a roadsection as a reference point by the transmitting side, the receivingside can precisely grasp a position at which an event occurs.

Seventh Embodiment

In Seventh Embodiment, an explanation will be given of a method oftransmitting position information for directly correlating respectivenode information and an event occurring at a corresponding node anddisplaying and transmitting these.

According to the method, as shown by FIG. 22(a), in node seriesinformation, successive to coordinate data of respective node numbers, acorresponding event occurring at a corresponding node is described by acorresponding event code and as shown by FIG. 12(b), event contentrepresented by the respective corresponding event code is described asevent details information.

Or, as shown by FIG. 23(a), in the node series information, only a codenumber and coordinate data are described, and as shown by FIG. 23 (b),as event information, event content and a node number at which eventoccurs are described.

According to the method, the event occurring position can be reproducedwith high accuracy.

Eighth Embodiment

In Eighth Embodiment, an explanation will be given of a method oftransmitting position information for transmitting position informationon a road by including information on a road including information in adirection of advancing a vehicle.

For example, there is a case in which traffic accident on a roadinfluences only running at an up road and does not influence running ata down road. In such occasion, according to traffic information, it isnecessary to transmit information of a position at which trafficaccident occurs and a road influenced by the traffic accident.

FIG. 24 schematically shows a state in which an event A (traffic stop)influencing a vehicle running in a direction of a vehicle advancingdirection 1 on a road and an event B (traffic lain regulation)influencing a vehicle running in a direction of a vehicle advancingdirection 2, occur.

At this occasion, position information on the road is transmitted to thereceiving side by data shown in FIGS. 25(a), 25(b), and 25(c).

FIG. 25(a) shows node series information specifying a road section.According to the node series information, there is prescribed adefinition of direction in which a forward direction with respect to anorder of aligning node series is defined as 2 and a rearward directionwith respect to the order of aligning the node series is defined as 1.FIG. 25(b) is road addition information similar to that in SixthEmbodiment (FIGS. 21(a), 21(b), and 21(c)).

FIG. 25(c) shows event information displaying an event content, arelative distance from a reference point as well as a vehicle advancingdirection influenced by the event by a direction identifying flagindicating the definition of direction with regard to respective event.That is, a vehicle running in a direction of a vehicle advancingdirection 1 is influenced by an event A and therefore, 1 defining arearward direction is displayed at the direction identifying flag and avehicle running in a direction of a vehicle advancing direction 2 isinfluenced by an event B and therefore, the direction identifying flagis displayed with 2 defining a forward direction.

On the receiving side receiving the data, the road section can bespecified by map matching with regard to an alignment in one directionof nodes P₁, P₂, . . . , P_(n) displayed by the node series informationand an event occurring position in the road section including thevehicle advancing direction can be specified based on relativeinformation and the direction identifying flag described in the eventinformation. Therefore, events in two directions can be expressed by mapdata in one direction and a data amount can be compressed.

Further, the direction identifying flag can also be used in the case ofdescribing an event occurring at one road of a double-streaked lineexplained in the fourth embodiment and as shown by FIG. 29, the factthat the event is an event which occurs at the road (FIG. 15) of theshape vector series identifying number 124 reproduced by mapping theroad (FIG. 14) of the shape vector series identifying number 123, can bedisplayed by the direction identifying flag (=1). Further, eventinformation at the road is displayed by using a node number (P_(n)′)after mapping as a node number.

Further, the direction identifying flag can also be used in the case ofdisplaying one way traffic of a road section specified by shape data andas shown by FIG. 26, in the case in which directions are defined suchthat a forward direction is defined as 1 and a rearward direction isdefined as 2 with regard to an order of aligning a node series, when aroad section specified by shape data constitutes one way traffic inP_(n)→P₁ direction, as shown by FIG. 27, one way traffic information canbe displayed by describing a direction identifying flag designating theone way traffic direction as 2 in the node series information. Further,the case of not constituting one way traffic is displayed by 0, (=notone way traffic).

On the receiving side receiving the node series information, inmatching, as shown by FIG. 28,

step 341: Receive node series information,

step 342: Execute map matching and sample road spot of matchingcandidate.

Step 343: Designate one way traffic of the candidate spot on map dataand compare the designated one way traffic with one way trafficdirection information of node series. When these coincide with eachother, the matching candidate is made to remain and when these do notcoincide with each other, the candidate is excluded from the matchingcandidate, the operation returns step 342 and samples a successivematching candidate.

In this way, by using the direction identifying flag, information of oneway traffic, information of a vehicle advancing direction influenced byan event which occurs can be transmitted by a small data amount.

Ninth Embodiment

In Ninth Embodiment, an explanation will be given of a method oftransferring position information transmitting travel time between twospots as traffic information.

According to the method, as shown by FIG. 30, two reference points (P₄,P_(X)) are set and travel time between the reference points istransmitted by data shown in FIGS. 31(a), 31(b), and 31(c).

FIG. 31(a) shows node series information for specifying a trafficsection including the two reference points. FIG. 31(b) shows roadadditional information similar to that of FIG. 21(b) explained in SixthEmbodiment. FIG. 31(c) shows necessary time information displayingtravel time, describing a start end side node number (P₄), a finish endside road number (P_(X)) and travel time therebetween.

On the receiving side receiving the information, by using the nodeseries information and the road additional information, the road sectioncan be specified by map matching and the travel time between thereference points can be recognized from the necessary time information.

Tenth Embodiment

In Tenth Embodiment, an explanation will be given of a method ofreproducing vector data series by which map matching is easy to executeon a receiving side receiving position information subjected to datacompression.

FIG. 32 shows a position information transmitting/receiving apparatus 10receiving and reproducing position information, further, generating andtransmitting position information informing event occurrence.

The apparatus 10 is provided with a position information receivingportion 11 for receiving position information transmitted from aposition information transmitting portion 21 of other apparatus 20, anode series restoring portion 12 for converting shape data included inthe position information into a vector data series which is easy toexecute map matching, a digital map data base 14 for accumulatingdigital map data, a map matching portion 13 for specifying a roadsection represented by the position information by executing mapmatching, a digital map displaying portion 15 for displaying the roadsection represented by the position information and an event position,an event inputting portion 16 for inputting information of an eventwhich occurs, a position information converting portion 17 forgenerating position information for transmitting an even occurringposition and a position information transmitting portion 18 fortransmitting the generated position information to a positioninformation receiving portion 22 of the other apparatus 20.

According to the apparatus 10, the position information receivingportion 11 receives the position information and the node seriesrestoring portion 12 converts shape data subjected to data compressionby approximation by a function included therein or thinning into a shapevector data series at equal intervals. FIG. 33(a) shows a shape vectordata series before compression and FIG. 33(b) shows data compressed bythinning and function approximation. The node series restoring portion12 restores a shape data series at equal intervals from data of FIG.33(b) as shown by FIG. 33(c).

The map matching portion 13 detects a road section matched to therestored shape vector data series from map data accumulated in thedigital map data base 14, further, specifies an event occurring positionof the road section and displays these to the digital map displayingportion 15.

Further, when even information is inputted from the event informationinputting portion 16, the position information converting portion 17generates position information for designating the road sectionincluding the event occurring position and the even occurring positionin the road section and the position information is transmitted from theposition information transmitting portion 18.

An explanation will be given of specific operation of the node seriesrestoring portion 12.

On the transmitting side, when the shape vector data series shown inFIG. 33(a) is acquired from map data, portions of the vector data seriesare approximated by a function F, further, at a linear portion, data isthinned to thereby transmit data having a compressed data amount.

Further, an explanation has been given of a method of approximating bythe function F in Third Embodiment. Further, a detailed explanation hasbeen given of a method of thinning data in Japanese Patent ApplicationNo. 242166/1999. In sum, among nodes included in the road section, nodeshaving a low degree of contributing to map matching are thinned and forsuch purpose, with regard to an azimuth from a contiguous node to acorresponding node, when a change in an azimuth from the correspondingnode to a successive node is equal to or smaller than predeterminedangle and a distance from the contiguous node to the corresponding nodeis less than a predetermined distance, the corresponding node isthinned.

By receiving data compressed in this way, the node series restoringportion 12 restores data at equal intervals as follows. In this case,data is restored such that the respective interval does not shift from aconstant distance A (meter) by ±b (meter) or more.

At a section in which data is thinned, an interval between P_(n−1)(X_(n−1), Y_(n−1)) and P_(n)(X_(n), Y_(n)) is regarded as a straightline and points are generated at an interval of A meter. Such a patternis shown in FIG. 47.

Here, when an azimuth from due north (Y direction) of P_(n−1)→P_(n)vector is designated by notation θ and generated points are designatedby notations P_(nm) (m=1, 2, 3, . . . ), the following relationships areestablished.X _(nm) =X _(n−1) +m×(A sin θ)Y _(nm) =Y _(n−1) +m×(A cos θ)

Further, at a section in FIG. 9(c) approximated by a function of a basicfunction F, as shown by FIG. 48, there is calculated a position P_(n−1)′(X_(n1)′, Y_(n1)′) advanced by L′ (at initial time, L′=A−b) when aninterval of P_(n−1)→P_(n) is assumed to be a straight line. In thiscase, coordinates of P_(n1)′ are as follows.X _(n1) ′=X _(n−1)+1×(L′ sin θ)Y _(n1) ′=Y _(n−1)+1×(L′ cos θ)

A point on the function F in correspondence with P_(n1)′ is designatedby notation P_(n1) (=F(P_(n1)′)). Under an X′-Y′ coordinates systemdefining P_(n−1)→P_(n) as X′ axis and an axis passing P_(n−1) andorthogonal to X′ axis as Y′ axis, an X′ coordinate of P_(n−1) is L′ anda Y′ coordinate of P_(n−1 is F ()1×L′) When the X′-Y′ coordinates systemis rotated by an angle (90-θ) and coordinate values thereof areconverted into coordinate values of an X-Y coordinates system, thecoordinates of P_(n1) (X_(n1), Y_(n1)) are as follows.X _(n1) =X _(n1) ′+{F(1×L′)sin(θ−90)}Y _(n1) =Y _(n1) ′+{F(1×L′)cos(θ−90)}

Here, when a distance L_(n1) between P_(n−1)→P_(n1) is within A+b(meter), the operation proceeds to calculation of P_(n2) When thedistance L_(n1) P_(n−1)→P_(n1) is larger than A+b (meter), calculationis executed again by setting L′=L′/2.

Thereafter, the calculating method of binary search is repeated.

By such a processing of the node series restoring portion 12, thecompressed data is converted into a coordinate series at equalintervals. Therefore, matching processing of the map matching portion 13is facilitated.

The processing of the node series restoring portion 12 may be realizedby software or may be realized by hardware formed by IC.

In this way, according to the method of the embodiment, a data series atequal intervals is restored from a data series subjected to datacompression and therefore, the matching processing is facilitated andaccuracy of map matching can be promoted.

Eleventh Embodiment

In Eleventh Embodiment, an explanation will be given of a method oftransmitting position information for transmitting a shape other thanthat of a road of digital map data.

Digital map data include a vector series (V) representing a shape of afacility as shown by FIG. 34, a vector series (X) representing a shapeof a prefectural boundary, a vector series (Y) representing a shape of alake or marsh and a vector series (W) representing a shape of contourlines as shown by FIG. 35. These shapes can be displayed by utilizingthe method of displaying a shape of a road which has been explainedabove, further, an event position thereof can be specified.

FIG. 36 shows shape data representing a shape of a house. A shape vectorkind is described as house and an identification code of a building or ageneral house each described as detailed information. Successively, anode total number and respective node coordinates representing a shapeof a house are described and an event occurring position is prescribedby a relative distance from a top node position.

FIG. 37 shows shape data representing a shape of a water area. A shapevector kind is described as water area and as detailed information, anidentification code of a face expressing water area such as lake or aline expressing water area such as river is described. The other is thesame as that in the case of a shape of a house.

FIG. 38 shows shape data representing a shape of an administrativeboundary. A shape vector kind is described as administrative boundaryand as detailed information, an identification code of a prefecturalboundary, a city boundary, or town boundary is described.

Further, FIG. 39 shows shape data representing a shape of a contourline. A shape vector kind is described as contour line and as detailedinformation, an identification code of contour line meters above sealevel is described.

By transmitting such position information, even when different kinds ofdigital maps are provided to the transmitting side and the receivingside, a house, a water area, an administrative boundary or a contourline can be identified by each other and an even occurring position canbe transmitted to each other.

Twelfth Embodiment

In Twelfth Embodiment, an explanation will be given of a method oftransmitting position information for transmitting a position other thanthat of a road on a digital map.

As shown by FIG. 40, when a position (reproduced position) outside of aroad indicated by a black triangle on a digital map is transmitted, thetransmitting side sets three reference points (event point 1, eventpoint 2, event point 3) and transmits to the receiving side, shape dataof a road section (map matching data 1) including the event point 1,data of a distance r₁ and an azimuth θ₁ from the event point 1 to thereproduced position, shape data of a road section (map matching data 2)including the event point 2, data of a distance r₂ and an azimuth θ₂from the event point 2 to the reproduced position, as well as, shapedata of a road section (map matching data 3) including the event point 3and data of a distance r₃ and an azimuth θ₃ from the event point 3 tothe reproduced position.

On the receiving side, the reproduced position is reproduced by aprocedure shown in FIG. 41.

Step 481: Execute map matching by using map matching data 1,

Step 482: Specify event point 1 on road.

Step 483: Calculate spot P₁ disposed at distance r₁, azimuth θ₁ fromevent point 1.

By repeating a similar procedure, the event point 2 is specified fromthe map matching data 2, a spot P₂ disposed at the distance r₂ and theazimuth θ₂ from the event point 2 is calculated, the event point 3 isspecified from the map matching data 3 and the spot P₃ disposed at thedistance and r₃ and the azimuth θ₃ from the event point 3 is calculated.

Step 484: Calculate gravitational center of point P₁, P₂, P₃,

Step 489: Constitute reproduced position by position of gravitationalcenter.

Further, as shown by FIG. 42, the three event points may be set on asingle road (map matching data). In this case, the reproduced positionviewed from the respective event point can be expressed by usingreference data (Δx_(n), Δy_(n)) of an x coordinate and a y coordinate.

On the receiving side receiving the position information, the reproducedposition is reproduced by a procedure shown in FIG. 43.

Step 501: Execute map matching by using map matching data,

Step 502: Specify event point 1 on road, Step 503: Calculate spot P₁ atΔx₁, Δy₁, from even point 1.

Similarly, step 502 and step 503 are repeated and the spot P₂ at Δx₂,Δy₂, from the event point 2 and the spot P₃ at Δx₃, Δy₃, from the eventpoint 3 are calculated.

Step 504: Calculate gravitational center of point P₁, P₂, P₃,

Step 505: Constitute reproduced position by position of gravitationalcenter.

In this way, a position outside of a road can be represented. Further,as the map matching data, other than that of road, there can also beutilized vector series representing a shape of a facility explained inThird Embodiment, vector series representing a shape of a prefecturalboundary, vector series representing a shape of a lake or marsh, or avector series representing a shape of a contour line.

Further, although in this case, there is shown a case of transmittingrelative information (information of distance and azimuth) from thethree reference points to a target position, even when relativeinformation from two reference points or one reference point istransmitted from the transmitting side, on the receiving side, thereference points can be specified with high accuracy on a digital map ofits own and therefore, by the relative information from the referencepoints, the target position can be calculated statistically.

Further, although according to the respective embodiments, coordinatesdata of respective nodes included in shape data are represented byabsolute values or relative values of longitude and latitude data, thecoordinates data of the respective nodes may be represented by usingother parameters.

For example, as shown by FIG. 49, when there are present nodes P_(j−1),P_(j) and P_(j+1) represented by xy coordinates as (x_(j−1), y_(j−1)),(x_(j), y_(j)) and (x_(j+1), y_(j+1)), a distance of a straight lineP_(j−1)→P_(j) is designated by notation L_(j), an absolute azimuth(angle in clockwise direction with north as a reference) of the straightline P_(j−1)→P_(j) is designated by notation ω_(j−1), a distance of astraight line P_(j)→P_(j+1) is designated by notation L_(j+1) and anabsolute azimuth of the straight line P→P_(j+1) is designated bynotation ω_(j), the node P_(j) can be specified by using the distanceL_(j) from the preceding node P_(j−1) and the absolute azimuth ω_(j−1).

Here, L_(j) and ω_(j−1) can be calculated from xy coordinate values ofP_(j−1) and P_(j) by the following equations.L _(j)={square root}{(x _(j) −x _(j−1))²+(y _(j) −y _(j−1))²}ω_(j−1)=tan⁻¹{(x _(j) −x _(j−1))/(y _(j) −y _(j−1))}

Also the node P_(j+1) can similarly be specified by using the distanceL_(j+1) from the preceding node P_(j) and the absolute azimuth ω_(j).

Further, the node P_(j+1) can also be specified by using the distanceL_(j+1) and an argument from the preceding node P_(j), that is, anazimuth difference Θ_(j) between the absolute azimuth ω_(j) ofP_(j)→P_(j+1) and the absolute azimuth ω_(j−1) of P_(j−1)→P_(j). Theargument Θ_(j) can be calculated from respective coordinate values ofP_(j−1), P_(j) and P_(j+1) by the following equation. $\begin{matrix}{\Theta_{j} = {\omega_{j} - \omega_{j - 1}}} \\{= {{\tan^{- 1}\left\{ {\left( {x_{j + 1} - x_{j}} \right)/\left( {y_{j + 1} - y_{j}} \right)} \right\}} - {\tan^{- 1}\left\{ {\left( {x_{j} - x_{j - 1}} \right)/\left( {y_{j} - y_{j - 1}} \right)} \right\}}}}\end{matrix}$

FIGS. 50(a), 50(b), and 50(c) exemplify transmitted data representingnode series information included in shape data by using a distance andan argument from a preceding node. The transmission data of FIG. 50(a)includes data of interpolation points #1 through #a between a node p₁and a node p₂ and the data of the interpolation points are constitutedby data of distances and arguments from preceding nodes or precedinginterpolation points. With regard to the node p₁ constituting a startend, the node p₁ includes data of absolute coordinates (longitude,latitude) representing a position and an absolute azimuth in a interceptdirection (absolute azimuth of a straight line connecting p₁ and theinterpolation point #1). Further, data of the interpolation point #1includes an argument data representing an argument difference between anabsolute azimuth of a straight line extending from the interpolationpoint #1 to the interpolation point #2 and the absolute azimuth in theintercept direction, and distance data from p₁ to the interpolationpoint #1 and data of the interpolation point #2 is similarly constitutedby using an argument data of an absolute azimuth of a straight lineextended from the interpolation point #2 to the interpolation point #3and the absolute azimuth of the straight line extended from theinterpolation point #1 to the interpolation point #2 and distance datafrom the interpolation point #1 to the interpolation point #2. The samegoes with the interpolation points #3 through #a.

Further, according to transmitted data of FIG. 50 (b), data ofrespective nodes excluding the node p₁ at the start end are constitutedby distances and arguments from preceding nodes.

FIGS. 51(a) and 51(b) schematically show a shape (a) of an object roadsection of original map data and a coordinate series (b) representingthe shape by distances and arguments from preceding nodes. Further, asshown by FIGS. 51(a) and 51(b), the nodes capable of reproducing theshape of the object road section by a smaller number from the originalmap data of the object road section may be resampled and the resamplednodes may be expressed by the distances and arguments from the precedingnodes.

FIG. 52 schematically shows a map matching processing on the receivingside receiving the transmitted data. According to the map matching, on adigital map of its own, firstly, candidate points in correspondence witha start end node p₁ of shape data are set. For that purpose, n pieces ofcandidates are set on n pieces of contiguous nodes substantially within200 m from a latitude and longitude data position of the start end nodep₁.

Next, distances D₁ from the position of the start end node p₁ torespective candidates P_(1,1) are calculated.

Next, as shown by FIG. 53, there is calculated a point P_(j+1,1)advanced from a current candidate point P_(j,1) of respective road by adistance L_(j) of an interval p_(j)→p_(j+1) of shape data along theroad, there are calculated an angle θ_(j,1) made by a straight lineconnecting P_(j−1,1)→P_(j,1) and a straight line connectingP_(j,1)→P_(j+1,1) and a difference□Δθ_(j,1)□ between the angle θ_(j,1)and a relative azimuth Θ_(j) of p_(j) represented by the shape data andan evaluation value ε_(j,1) is calculated by the following equation.ε_(j,1) =α×D ₁+Σ(β×□Δθ_(j,1)□)(Σ designates addition of J=1 to j)

-   -   α: predetermined coefficient    -   β: predetermined coefficient.

Next, the candidate point P_(j,1) is moved to the candidate pointP_(j+1,1).

Such a processing is repeated for all of the candidate points, further,a similar processing is executed for all of nodes included in the shapedata. When the processing has been finished for all of the nodesincluded in the shape data, a candidate having the least operation valueε_(i) is selected as the object load.

According to the map matching processing, by using “distance L₁ from thepreceding node” included in shape data, a successive candidate point caneasily be calculated, further, the evaluation value can be calculated bydirectly using “relative azimuth” included in the shape data. Therefore,processing load of the map matching on the receiving side is alleviated.

Further, according to the method of transmitting position information ofthe invention, operational procedures of computer on transmitting sideand receiving side apparatus can be realized by prescribing theprocedure by programs.

While only certain embodiments of the invention have been specificallydescribed herein, it will be apparent that numerous modifications may bemade thereto without departing from the spirit and scope of theinvention.

The present invention is based on Japanese Patent Applications No.2000-375320 filed on Dec. 8, 2000, and No. 2001-220062 filed on Jul. 19,2001, which are incorporated herein by references.

INDUSTRIAL APPLICABILITY

As apparent from the above-described explanation, according to themethod of transmitting position information of a digital map of theinvention, positions of the digital map can efficiently and accuratelybe transmitted.

According to a method of transmitting shape data by adding azimuthinformation, height information or one way traffic information by adirection identifying flag, accuracy of matching can be promoted and anecessary period of time of matching can be shortened.

Further, according to a transmitting method for approximating a shapedata series by a function or displaying shape data of a double-streakedline by an offset distance, a data amount can be reduced and a datatransmission efficiency can be promoted.

Further, according to a transmitting method for displaying a relativedistance up to an event position by setting a reference point at acrossroads or the like in a road section, or prescribing an eventposition by a node number, accuracy of specifying the event position onthe receiving side can be promoted.

Further, by using a direction identifying flag, a direction of advancinga vehicle influenced by an event can be specified.

Further, according to a method and apparatus for restoring data at equalintervals from a compressed shape data series, a matching efficiency onthe receiving side can be promoted.

Further, according to the transmitting method of the invention, traveltime can be transmitted, further, data can be transmitted in the form ofnot infringing copyright of map data.

Further, the invention is applicable also to transmission of vector dataother than that of a road, further, a position outside of a road on adigital map can also be transmitted.

1. A method of identifying a location on two different digital maps,comprising the steps of: creating location information includingcoordinates of a first point on a first digital map, and interceptazimuth information of said first point; and identifying a location of asecond point on a second digital map by using said location information,wherein said second point corresponds to said first point.
 2. A methodof identifying a location on two different digital maps, comprising thesteps of: creating location information including coordinates of a firstpoint on a first digital map, and height information of said firstpoint; and identifying a location of a second point on a second digitalmap by using said location information, wherein said second pointcorresponds to said first point.
 3. The method of identifying a locationon two different digital maps according to claim 2, wherein altitudedata is employed as said height information.
 4. The method ofidentifying a location on two different digital maps according to claim2, wherein gradient data is employed as said height information.
 5. Themethod of identifying a location on two different digital maps accordingto claim 2, wherein a difference of elevation is employed as said heightinformation.
 6. A method of identifying a location on two differentdigital maps, comprising the steps of: creating location informationincluding coordinates of a first point on a first digital map, andfunction information approximating a first shape passing through atleast said first point; identifying a second shape on a second digitalmap by using said function information, wherein said second shapecorresponds to said first shape; and identifying a location of a secondpoint on the second digital map by using said identified second shape,wherein said second point corresponds to said first point.
 7. A methodof identifying a location on two different digital maps, comprising thesteps of: creating location information including coordinates of a firstpoint on a first digital map, coordinates of a first reference point,and a distance and a direction of an offset from said first point tosaid first reference point; identifying a location of a second referencepoint on a second digital map by using said first reference point,wherein said second reference point corresponds to said first referencepoint; and identifying a location of a second point on the seconddigital map by using said identified second reference point and saiddistance and said direction of said offset from said first point to saidfirst reference point, wherein said second point corresponds to saidfirst point.
 8. The method of identifying a location on two differentdigital maps according to claim 7, wherein said first reference pointrepresents one way road of an up-and-down-ways separating road.
 9. Themethod of identifying a location on two different digital maps accordingto claim 7, wherein said first reference point represents a middle lineof an up-and-down-ways separating road.
 10. A method of identifying alocation on two different digital maps, comprising the steps of:creating location information including shifted coordinates of a firstpoint without mis-identifying a second point on a second digital map,wherein an amount of said shifting coordinates is set depending on adistance between said first shape and a road lying next to said firstshape, and a direction of said shifting coordinates is set randomly; andidentifying a location of said second point on said second digital mapby using said shifted coordinates, wherein said second point correspondsto said first point.
 11. A method of identifying a location on twodifferent digital maps, comprising the steps-of: creating locationinformation including coordinates of a first point on a first digitalmap, wherein said coordinates of said first point are represented with arelative distance from a basing point set randomly; and identifying alocation of point on a second digital map by using said locationinformation.
 12. A method of identifying a location on two differentdigital maps, comprising the steps of: creating location informationincluding coordinates of a first point on a first digital map, andobject information directly associated with said coordinates of saidfirst point; and identifying a location of point on a second digital mapby using said location information.
 13. The method of identifying alocation on two different digital maps according to claim 12, wherein,in the step of creating location information, direction information isincluded in said location information, and wherein said directioninformation indicates a traveling direction of vehicle with an influenceof the object represented with said object information.
 14. The methodof identifying a location on two different digital maps according toclaim 13, wherein said object is a point of interest.
 15. The method ofidentifying a location on two different digital maps according to claim13, wherein said object is a specific route.
 16. A method of identifyinga location on two different digital maps, comprising the steps of:creating location information including coordinates of a first point ona first digital map and direction information indicating a status of aregulation of one-way traffic on a road having said first point;identifying a location of point on a second digital map by using saidlocation information, wherein said second point corresponds to saidfirst point.
 17. A method of identifying a location on two differentdigital maps, comprising the steps of: setting a first reference pointon a first digital map; creating a location information includingcoordinates of a first point on the first digital map and traveling timefrom said reference point to said first point; identifying a location ofreference point on a second digital map by using said locationinformation, wherein said second reference point corresponds to saidfirst reference point; and identifying a location of a second point onthe second digital map by using said second reference point and saidlocation information, wherein said second point corresponds to saidfirst point.
 18. A method of identifying a location on two differentdigital maps, comprising the steps of: setting first reference point ona first road on a first digital map; creating location informationincluding: coordinates of said reference point, and relative coordinatesof a first point indicating a location of an object, to said firstreference point; identifying a location of reference point on a secondroad on a second digital map by using said location information, whereinsaid second reference point corresponds to said first reference pointand said second road corresponds to said first road; and identifying alocation of a second point on the second digital map by using saididentified second reference point and said relative coordinates of saidfirst point, wherein said second point corresponds to said first point.19. A method of identifying a location on two different digital maps,comprising the steps of: setting first points on a first digital map,said first points representing a first shape; creating first locationinformation including coordinates of each of said first points; creatingsecond location information including coordinates of second points byusing said first location information, wherein said coordinate of secondpoints are set by modifying coordinates of said first points andinterpolating new points; and identifying a location of a second shapeon the second digital map by using said created second locationinformation, wherein said second shape corresponds to said first shape.20. A method of identifying a location on two different digital maps,comprising the steps of: extracting first coordinates of a first pointfrom a first digital map; calculating a first azimuth at said firstpoint; creating location information including said first coordinatesand said first azimuth; extracting candidate points on a second digitalmap, said candidate points near to a place indicated by said firstcoordinates; calculating each azimuth of said each candidate point;calculating each difference between said first azimuth and each azimuthof said candidate point; comparing said each difference with a thresholdvalue; removing one or more candidate points whose azimuth differs fromsaid first azimuth more than said threshold value; and identifying alocation of a second point on a second digital map by using one or moreremaining candidate points, wherein said second point corresponds tosaid first point.
 21. A method of identifying a location on twodifferent digital maps, comprising the steps of: extracting firstcoordinates of a first point and a first road next to said first pointfrom a first digital map; calculating a distance from said first pointto said first road; determining a shift amount of said first point basedon said calculated distance; shifting said first point with saiddetermined shift amount and a random direction; calculating firstshifted coordinates indicating said shifted first point; and identifyinga location of a second point on a second digital map by using said firstshifted coordinates, wherein said second point corresponds to said firstpoint.
 22. A method of identifying a location on two different digitalmaps, comprising the steps of: extracting coordinates of first pluralpoints from a first digital map; calculating relative coordinates of afirst object point to said first plural points; identifying secondplural points on a second digital map by using said coordinates of saidfirst plural points, wherein said second plural points correspond tosaid first plural points; and identifying a location of a second objectpoint on the second digital map by using identified second plural pointsand said relative coordinates of said first object point, wherein saidsecond object point corresponds to said first object point.
 23. A methodof identifying a location on two different digital maps, comprising thesteps of: extracting first coordinates of a first point from a firstdigital map; creating function information approximating a first shapepassing through at least said first point; reproducing a second shapefrom said function information; and identifying a location of a secondpoint on a second digital map by using said second shape and said firstcoordinates, wherein said second point corresponds to said first point.